(1) Background: Dialectical Behaviour Therapy (DBT) is the recommended treatment for Borderline Personality Disorder (BPD) symptoms in adults, however, research investigating the effectiveness of DBT for adolescents is limited. The present study explores the experiences of young people and their parents/carers of a DBT service using qualitative methodology. (2) Methods: Young people and their parents/carers, who completed DBT within the National and Specialist Child and Adolescent Mental Health DBT Service based at the Maudsley Hospital in London, were asked questions regarding their experience of the service. Data was collected from young people who completed treatment between July 2019 and July 2020 ( 18) and their parents and carers ( = 7). (3) Results: Amongst young people, the themes identified were: a new way of living, better understanding of self, new skills, person-centred approach, and relationships with others. Parent and carer interviews revealed themes of improved relationships, feeling supported, improved quality of life, and time/timing. (4) Conclusions: Young people reported improvements in emerging BPD symptomology after completing DBT. Parents and carers reported improvements in their young person and families since starting DBT. A longer DBT programme, earlier DBT intervention, and the time-consuming nature of DBT were highlighted as areas for improvement.